Bitcoin/Litecoin: Generate Signature

Bitcoin and Litecoin chains support the following signature kinds:

• Psbt: Fully sign a PSBT, partially signed bitcoin transaction.

• Bip322: Generates the signature for a generic message defined in BIP-322.

PSBT Signature

Property	Type	Description
kind*	String	Psbt
psbt*	Hex String	The hex encoded PSBT as shown below
externalId	(Optional) String	A unique ID from your system. It can be leveraged to be used as an idempotency key (read more here)

Sample request body

{
  "kind": "Psbt",
  "psbt": "0x70736274ff0100710200000001ca17431a33a13d3ef8bfb041c8546071f9d3a609abe3c91efbed83265e1426730100000000ffffffff02e803000000000000160014a40a65b46ff36c53f1afb8e35e25a4c0bcfc9979d6d1150000000000160014237ad8ba2ffd992f6ebc7ab388e77f00fc87d1c9000000000001011f54d6150000000000160014237ad8ba2ffd992f6ebc7ab388e77f00fc87d1c9000000"
}

200 response example

{
  "id": "sig-7dmih-01orr-xxxxxxxxxxxxxxxx",
  "walletId": "wa-36a0p-pdil7-xxxxxxxxxxxxxxxx",
  "network": "BitcoinTestnet3",
  "requester": {
    "userId": "us-3v1ag-v6b36-xxxxxxxxxxxxxxxx",
    "tokenId": "to-7mkkj-c831n-xxxxxxxxxxxxxxxx",
    "appId": "ap-341e6-12nj6-xxxxxxxxxxxxxxxx"
  },
  "requestBody": {
    "kind": "Psbt",
    "psbt": "0x70736274ff0100710200000001cd290edbff81f3762b1c9a6f6532f5f2d3d1e48a850d4285b8606bbceb96ee790000000000ffffffff020100000000000000160014a40a65b46ff36c53f1afb8e35e25a4c0bcfc99794d25000000000000160014237ad8ba2ffd992f6ebc7ab388e77f00fc87d1c9000000000001011fe425000000000000160014237ad8ba2ffd992f6ebc7ab388e77f00fc87d1c9000000"
  },
  "status": "Signed",
  "signatures": [
    {
      "r": "0xe10a3e24bb0b0a5feae39997d05b5d1ce0e123f78c979914ea3394962f7995f6",
      "s": "0x727190270d14e58acbcfa98a765fd4c50b51afb7d1ef8152cd79d562f28a1bbc",
      "recid": 0,
      "encoded": "0x3045022100e10a3e24bb0b0a5feae39997d05b5d1ce0e123f78c979914ea3394962f7995f60220727190270d14e58acbcfa98a765fd4c50b51afb7d1ef8152cd79d562f28a1bbc"
    }
  ],
  "signedData": "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",
  "dateRequested": "2024-01-10T19:15:21.572Z",
  "dateSigned": "2024-01-10T19:15:21.859Z"
}

Typescript Example with BitcoinJS

First install the BitcoinJS SDK. You can find the full documentation here: https://github.com/bitcoinjs/bitcoinjs-lib

Here a code sample to generate a signature via the Dfns TypeScript SDK:

import { networks, payments, Psbt } from 'bitcoinjs-lib'
import axios from 'axios'

const walletId = 'wa-6lbfv-9esgj-xxxxxxxxxxxxxxxx'
const wallet = await dfnsClient.wallets.getWallet({ walletId })
const publicKey = Buffer.from(wallet.signingKey.publicKey, 'hex')

const network = networks.testnet
const { address } = payments.p2wpkh({
  pubkey: publicKey,
  network,
})

const txid = '87872516c6e93f136fc6c493c7172596b11c695e27889de7532abffcac2a4b5e'
const n = 1
const utxo = (
  await axios.post(BITCOIN_NODE_URL, {
    jsonrpc: '2.0',
    id: 'gettxout',
    method: 'gettxout',
    params: [txid, n, false],
  })
).data.result

const balance = utxo.balance * 100000000
const amount = 1
const fee = 150

const psbt = new Psbt({ network })
psbt.addInput({
  hash: txid,
  index: n,
  witnessUtxo: {
    script: Buffer.from(utxo.scriptPubKey.hex, 'hex'),
    value: balance,
  },
})

psbt.addOutput({
  address: 'tb1q5s9xtdr07dk98ud0hr34ufdycz70exte2kehm2',
  value: amount,
})

psbt.addOutput({
  address,
  value: balance - amount - fee,
})

const res = await dfnsClient.wallets.generateSignature({
  walletId,
  body: { kind: 'Psbt', psbt: `0x${psbt.toHex()}` },
})

BIP-322 Generic Message Signature

Generates the signature for a generic message defined in BIP-322.

Request body

Property	Type	Description
kind*	String	Bip322
message*	String	The generic message hex encoded.
format	(Optional) String	Either Simple or Full. Defaults to Simple if not present. The formatted signature is returned in the signedData field in the response.
externalId	(Optional) String	A unique ID from your system. It can be leveraged to be used as an idempotency key (read more here)

Sample request body

{
  "kind": "Bip322",
  "message": "0x49206c6f76652044666e73"
}

200 response example

{
  "id": "sig-7dmih-01orr-xxxxxxxxxxxxxxxx",
  "walletId": "wa-36a0p-pdil7-xxxxxxxxxxxxxxxx",
  "network": "BitcoinTestnet3",
  "requester": {
    "userId": "us-3v1ag-v6b36-xxxxxxxxxxxxxxxx",
    "tokenId": "to-7mkkj-c831n-xxxxxxxxxxxxxxxx",
    "appId": "ap-341e6-12nj6-xxxxxxxxxxxxxxxx"
  },
  "requestBody": {
    "kind": "Bip322",
    "hash": "0x49206c6f76652044666e73"
  },
  "status": "Signed",
  "signature": {
    "r": "0x883613c2f19e4ab70f82c533950fb9060ac366a3a64d77950c89866dfe07c926",
    "s": "0x3fb815f34db5ebc9e97dee46500b75494717cb69adec5f01e17b4a58c50f9bfa",
    "recid": 1,
    "encoded": "0x3045022100883613c2f19e4ab70f82c533950fb9060ac366a3a64d77950c89866dfe07c92602203fb815f34db5ebc9e97dee46500b75494717cb69adec5f01e17b4a58c50f9bfa"
  },
  "signedData": "0x02483045022100883613c2f19e4ab70f82c533950fb9060ac366a3a64d77950c89866dfe07c92602203fb815f34db5ebc9e97dee46500b75494717cb69adec5f01e17b4a58c50f9bfa012103e6be69fe373e07962698243fb3d41b5b24e16a461866bd1813afcf9b53e1da6e",
  "dateRequested": "2024-10-25T17:47:48.068Z",
  "dateSigned": "2024-10-25T17:47:48.749Z"
}